HTML (Hypertext Markup Language) is the standard markup language used to create web pages. It uses tags to structure paragraphs, headings, links and other content. HTML files are read by browsers to display web pages. HTML documents consist of elements made up of opening and closing tags that define the structure and layout of content on a web page. Common block-level elements like <html>, <head> and <body> define overall page structure, while inline elements format text within blocks.